Yeahey...
Was testing it again yesterday, trying to figure out the problem with changing seats in the bombercrew. It was working fine for a while as long as I didn´t touch the stick while changing places inside the bomber. But changing place and pulling hard on the stick at the same time, caused the script to think that I left the plane. So guess this is/was an error in the game and the broken netcode or the way positions are calculated, not the script.